1. Field of the Invention
The present invention relates to a wheel motor provided with a reduction gear for use in an electric automobile.
2. Description of the Prior Art
In recent years, in view of environmental problems, electric automobiles have been extensively developed. Several types of electric automobiles have been developed. In one type, an electric motor is substituted for a conventional engine and is connected to a drive shaft, or the electric motor is connected to a power transmission shaft to drive a pair of front wheels or rear wheels. In another type, plural wheel motors provided with reduction gears or mechanisms are used, with each motor being directly connected to a corresponding wheel through reduction gears.
The latter type employing plural wheel motors provided with reduction gears has been described in Japanese Laid-Open Patent Publication No. 62-175217. That publication describes an arrangement wherein each reduction gear is located inside a wheel and axially (i.e. laterally) outside the motor. Such wheel motors and reduction gears are used in dump trucks for mines and other applications associated with duplex tires. In such applications there are no severe restrictions on the dimensions of the driving mechanisms.
However, if one were to attempt to apply the above wheel motors reduction gears to general use automobile wheels, the motor would protrude from each wheel (because the wheel is only a single tire wheel) and thus the motor would be susceptible to damage if a wheel leaves the road and also susceptible to damage by a stone striking the wheel under ordinary driving conditions.
Further, in wheel motors provided with reduction gears, it is necessary to prevent interference between the vehicle body and the motor and reduction gears during vertical movement and steering of the wheels. These considerations dictate a compact design for the motor and reduction gear to allow installation in a limited space.
In electric automobiles, it is also necessary to use motors having small and light structures as well as large output torques to obtain high power relative to the vehicle weight.
It is therefore an object of this invention to provide a wheel motor provided with reduction gearing which overcomes the above-noted problems and in which the motor dimensions are reduced, and high output power and a compact structure are achieved.